Beneficial insects, particularly the honeybee, are susceptible to infestation and damage caused by parasitic mites. Recently, a plague of parasitic mites has significantly decreased the honeybee population. Honeybees are important for crop pollination and aid in fruit formation and size and enhance crop yield. Measures of control of the parasitic mite populations are few and unpredictable.
Parasitic and saprophagous mites are a serious threat for many cultured insects used for scientific research and for production of insect hosts for biocontrol agents. Saprophagous mites such as Histiostoma sp. and parasitic mites such as Proctolaelaps sp. may cause significant loss of Drosophila stock cultures commonly used for scientific research. Decreased fitness of mite-infested Drosophila cultures may complicate the interpretation of genetic crosses. Moreover, various parasitic and saprophagous mite species greatly interfere with the rearing of roaches, house flies, beetles, crickets, white flies, thrips, aphids, and lepidoptera. The inability to effectively control mite infestations using conventional methods may result in the loss of valuable insect cultures. Further, production of extremely large insect colonies such as those used for silkworm production, for bait, for sterile insect release programs, (i.e. the Mediterranean Fruit Fly, Gypsy Moth, Screwworm Fly) and the like, are vulnerable to mite infestation and the damage and loss caused thereby. Also, the propagation of biocontrol agents such as Diptera (Spalagiodae and Tachinidae) for the biocontrol of flies (Diptera) and Hymenoptera (Trichogrammatidae, Ichneumonidae, Braconidae, Apidae, Eulophidae, Chalcididae, and Spalangiadae) for the biocontrol of Lepidoptea, Coleoptera, Diptera and Homoptera require healthy insect hosts. The propagation of viral biocontrol agents (baculoviruses, granuloviruses, and emtomapox viruses) may also be seriously affected by the presence of mites. Currently there are no effective means to rid insect colonies of these dangerous parasitic and saprophagous mites.
Therefore, new methods are needed to provide selective control of parasitic and saprophagous mites on beneficial insects and protection of said insects from infestation and damage caused by parasitic and saprophagous mites with little or no concommitant harm to the beneficial host insect.
The present invention provides a method for the protection of beneficial insects from infestation and damage caused by parasitic or saprophagous mites which comprises applying to said insects, their breeding ground or habitat a parasiticidally effective amount of a mitochondrial electron transport inhibitor or a formula I pyrimidine compound 
wherein
X1 and X2 are each independently O, S(O)n, CO, CH2, or NR;
n is 0, 1, or 2;
R is hydrogen or C1-C6alkyl;
R1 and R10 are each independently hydrogen or halogen;
R2 and R9 are each independently hydrogen, halogen, CN, NO2, C1-C6haloalkyl, C1-C6alkoxy, C1-C6alkylthio, NR11R12, C1-C6alkoxycarbonyl or C1-C6alkyl optionally substituted with one or more C1-C4alkoxy or C1-C4 haloalkoxy groups;
R11 and R12 are each independently hydrogen or C1-C6alkyl;
R3 and R8 are each independently hydrogen, chlorine, CN, NO2, C1-C6haloalkyl, C2-C6haloalkenyl, C2-C6haloalkynyl, C1-C6haloalkoxy, C1-C6haloalkylthio, C1-C6haloalkylsulfinyl, C1-C6haloalkylsulfonyl, C1-C6haloalkoxycarbonyl, or C1-C6alkyl optionally substituted with one or more C1-C4alkoxy groups;
R4 and R7 are each independently hydrogen, halogen, C1-C6alkyl or C1-C6alkoxy;
R5 is hydrogen, halogen, CN, C1-C6alkyl, C1-C6haloalkyl, C1-C6alkoxy, C1-C6alkylthio, C1-C6alkylsulfinyl or phenyl; and
R6 is hydrogen, or when R5 is hydrogen, C1-C6alkyl.
Preferred formula I compounds are those wherein either each of the two phenyl rings is unsubstituted or at least one of R3 and R8 is other than hydrogen.
As used herein the term xe2x80x9cparasiticidally effectivexe2x80x9d is defined to be less than the effective LD50 for the beneficial insect (dosage rate required to obtain 50% mortality of healthy uninfected insects), but sufficient to control or suppress the infestation of parasitic mites and/or saprophagous mites.
The invention further provides a method for the selective control of parasitic mites in the presence of beneficial insects.
Beneficial insects such as Apidae, for example, Apinae (honeybees), Bombinae (bumblebees) and Euglossinae (orchid bees) are susceptible to attack and infestation by parasitic mites, particularly mites such as Varroa jacobsoni (Varroa mites), Acarapis woodi (tracheal mites) and Tropilaelaps clareae. These parasites feed on the insect""s blood via the trachea (tracheal mites), via the cuticle from the brood or adult (Varroa mites) or the larvae (T. clareae) causing physical deformation, deterioration and death. Further, parasitic mites may either transmit or xe2x80x9ctriggerxe2x80x9d viruses in honeybees and other beneficial insects. Currently, a plague of parasitic mites has caused significant global concern over the present and future populations of essential agronomically important insects such as the honeybee.
Further, saprophagous mites such as Histiostoma sp. and parasitic mites such as Proctolaelaps sp. cause significant loss of Drosophila stock cultures commonly used for scientific research. Various parasitic and saprophagous mite species greatly interfere with the rearing of roaches, houseflies, beetles, crickets, white flies, thrips, aphids, and lepidoptera. Mite infestation control on beneficial insects using conventional miticidal methods currently results in the loss of valuable insect cultures, decreased propagation of biocontrol agents which require healthy insect hosts, and decreased propagation of viral biocontrol agents.
Effective miticides that discriminate between the insect host and parasitic or saprophagous mites have heretofore not been identified. The performance of current miticides on beneficial insects yields unpredictable results and incomplete control.
Surprisingly, it has now been found that a mitochondrial electron transport inhibitor or a formula I pyrimidine compound may be used to effectively control parasitic and saprophagous mites in the presence of beneficial insects and for the protection of said insects from the infestation and damage caused by parasitic and saprophagous mites. Advantageously, the method of the invention may be used to control both the Varroa mite and the tracheal mite in the presence of beneficial insects, particularly honeybees, with little or no significant harmful effect to the insect host. Further, the method of the invention may be used to control parasitic and saprophagous mite populations in insect colonies committed to scientific research and the production of insect biocontrol agents.
Mitochondrial electron transport inhibitors, hereinafter designated METI, such as pyrazole carboxamides, quinones, thioureas, quinazolines, pyridazinones, pyrimidinamines, and the like all interfere with mitochondrial transport. It has now been found that these particular inhibitors are useful for the selective control of parasitic and saprophagous mites in the presence of beneficial insects.
Among the METI preferred for use in the method of invention are fenpyroximate, acequinocyl, diafenthiuron, fenazaquin, pyridaben and pyrimidifen.
Many pyrimidine compounds, including the formula I pyrimidine compounds, methods for their preparation and the insecticidal and acaricidal uses thereof are described in U.S. Pat. No. 5,707,995 and WO 98/12184. Among the broad class of pyrimidine compounds described, surprisingly, it has now been found that those particular pyrimidine compounds of formula I are useful for the protection of beneficial insects from infestation and damage caused by parasitic mites.
Preferred pyrimidine compounds of formula I useful in the method of the invention are those compounds wherein X1 and X2 are each O or NR;
R1, R3, R8 and R10 are each independently hydrogen or trifluoromethyl, with the proviso that at least one of R1, R3, R8, and R10 must be trifluoromethyl;
R2 and R9 are each independently hydrogen, chlorine or fluorine; and
R4, R5, R6, and R7 are hydrogen.
More preferred formula I pyrimidine compounds useful in the inventive method are 4-[(4-chloro-xcex1,xcex1,xcex1-trifluoro-m-tolyl)oxy]-6-[(xcex1,xcex1,xcex1, 4-tetrafluoro-m-tolyl)oxy]-pyrimidine; 4-(xcex1,xcex1, xcex1,4-tetrafluoro-N-methyl-m-toluidino)-6-[(xcex1,xcex1,xcex1, 4-tetrafluoro-m-tolyl)oxy]pyrimidine; and 4,6 bis[(xcex1,xcex1,xcex1, 4-tetrafluoro-m-tolyl)oxy]pyrimidine.
In actual practice a METI or formula I pyrimidine compound may be applied to the beneficial insect breeding ground or habitat such as a beehive, nest, brood chamber, or the like using a conventional delivery system. For example, formula I pyrimidines or METI may be applied to mite-infested beneficial insect colonies or research laboratory insect cultures in the form of diet incorporation, or by insertion into the colony or culture of an impregnated strip, or by utilization of available standard delivery systems. Effective amounts of the METI or formula I pyrimidine compound will vary according to the miticidal sensitivity of the beneficial insect species, the degree of mite infestation, the insect population density, habitat construction, weather conditions, the timing of the beneficial insect life cycle, and the like. In general, parasiticidally effective amounts may be about 0.001-10 xcexcg per insect.